libata: convert to using sg helpers

This converts libata to using the sg helpers for looking up sg
elements, instead of doing it manually.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

2 files changed, 26 insertions, 20 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 68699b3e7998..e52c33180e42 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -1410,7 +1410,7 @@ static void ata_qc_complete_internal(struct ata_queued_cmd *qc)
  */
 unsigned ata_exec_internal_sg(struct ata_device *dev,
                               struct ata_taskfile *tf, const u8 *cdb,
-                              int dma_dir, struct scatterlist *sg,
+                              int dma_dir, struct scatterlist *sgl,
                               unsigned int n_elem, unsigned long timeout)
 {
         struct ata_link *link = dev->link;
@@ -1472,11 +1472,12 @@ unsigned ata_exec_internal_sg(struct ata_device *dev,
         qc->dma_dir = dma_dir;
         if (dma_dir != DMA_NONE) {
                 unsigned int i, buflen = 0;
+                struct scatterlist *sg;
 
-                for (i = 0; i < n_elem; i++)
-                        buflen += sg[i].length;
+                for_each_sg(sgl, sg, n_elem, i)
+                        buflen += sg->length;
 
-                ata_sg_init(qc, sg, n_elem);
+                ata_sg_init(qc, sgl, n_elem);
                 qc->nbytes = buflen;
         }
 
@@ -4292,7 +4293,7 @@ void ata_sg_clean(struct ata_queued_cmd *qc)
                 if (qc->n_elem)
                         dma_unmap_sg(ap->dev, sg, qc->n_elem, dir);
                 /* restore last sg */
-                sg[qc->orig_n_elem - 1].length += qc->pad_len;
+                sg_last(sg, qc->orig_n_elem)->length += qc->pad_len;
                 if (pad_buf) {
                         struct scatterlist *psg = &qc->pad_sgent;
                         void *addr = kmap_atomic(psg->page, KM_IRQ0);
@@ -4547,6 +4548,7 @@ void ata_sg_init_one(struct ata_queued_cmd *qc, void *buf, unsigned int buflen)
         qc->orig_n_elem = 1;
         qc->buf_virt = buf;
         qc->nbytes = buflen;
+        qc->cursg = qc->__sg;
 
         sg_init_one(&qc->sgent, buf, buflen);
 }
@@ -4572,6 +4574,7 @@ void ata_sg_init(struct ata_queued_cmd *qc, struct scatterlist *sg,
         qc->__sg = sg;
         qc->n_elem = n_elem;
         qc->orig_n_elem = n_elem;
+        qc->cursg = qc->__sg;
 }
 
 /**
@@ -4661,7 +4664,7 @@ static int ata_sg_setup(struct ata_queued_cmd *qc)
 {
         struct ata_port *ap = qc->ap;
         struct scatterlist *sg = qc->__sg;
-        struct scatterlist *lsg = &sg[qc->n_elem - 1];
+        struct scatterlist *lsg = sg_last(qc->__sg, qc->n_elem);
         int n_elem, pre_n_elem, dir, trim_sg = 0;
 
         VPRINTK("ENTER, ata%u\n", ap->print_id);
@@ -4825,7 +4828,6 @@ void ata_data_xfer_noirq(struct ata_device *adev, unsigned char *buf,
 static void ata_pio_sector(struct ata_queued_cmd *qc)
 {
         int do_write = (qc->tf.flags & ATA_TFLAG_WRITE);
-        struct scatterlist *sg = qc->__sg;
         struct ata_port *ap = qc->ap;
         struct page *page;
         unsigned int offset;
@@ -4834,8 +4836,8 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)
         if (qc->curbytes == qc->nbytes - qc->sect_size)
                 ap->hsm_task_state = HSM_ST_LAST;
 
-        page = sg[qc->cursg].page;
-        offset = sg[qc->cursg].offset + qc->cursg_ofs;
+        page = qc->cursg->page;
+        offset = qc->cursg->offset + qc->cursg_ofs;
 
         /* get the current page and offset */
         page = nth_page(page, (offset >> PAGE_SHIFT));
@@ -4863,8 +4865,8 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)
         qc->curbytes += qc->sect_size;
         qc->cursg_ofs += qc->sect_size;
 
-        if (qc->cursg_ofs == (&sg[qc->cursg])->length) {
-                qc->cursg++;
+        if (qc->cursg_ofs == qc->cursg->length) {
+                qc->cursg = sg_next(qc->cursg);
                 qc->cursg_ofs = 0;
         }
 }
@@ -4959,7 +4961,7 @@ static void __atapi_pio_bytes(struct ata_queued_cmd *qc, unsigned int bytes)
                 ap->hsm_task_state = HSM_ST_LAST;
 
 next_sg:
-        if (unlikely(qc->cursg >= qc->n_elem)) {
+        if (unlikely(qc->cursg == sg_last(qc->__sg, qc->n_elem))) {
                 /*
                  * The end of qc->sg is reached and the device expects
                  * more data to transfer. In order not to overrun qc->sg
@@ -4982,7 +4984,7 @@ next_sg:
                 return;
         }
 
-        sg = &qc->__sg[qc->cursg];
+        sg = qc->cursg;
 
         page = sg->page;
         offset = sg->offset + qc->cursg_ofs;
@@ -5021,7 +5023,7 @@ next_sg:
         qc->cursg_ofs += count;
 
         if (qc->cursg_ofs == sg->length) {
-                qc->cursg++;
+                qc->cursg = sg_next(qc->cursg);
                 qc->cursg_ofs = 0;
         }
 
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 229a9ff9f924..377e6d4d9be3 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -29,7 +29,7 @@
 #include <linux/delay.h>
 #include <linux/interrupt.h>
 #include <linux/dma-mapping.h>
-#include <asm/scatterlist.h>
+#include <linux/scatterlist.h>
 #include <linux/io.h>
 #include <linux/ata.h>
 #include <linux/workqueue.h>
@@ -416,6 +416,7 @@ struct ata_queued_cmd {
         unsigned long           flags;          /* ATA_QCFLAG_xxx */
         unsigned int            tag;
         unsigned int            n_elem;
+        unsigned int            n_iter;
         unsigned int            orig_n_elem;
 
         int                     dma_dir;
@@ -426,7 +427,7 @@ struct ata_queued_cmd {
         unsigned int            nbytes;
         unsigned int            curbytes;
 
-        unsigned int            cursg;
+        struct scatterlist      *cursg;
         unsigned int            cursg_ofs;
 
         struct scatterlist      sgent;
@@ -1043,7 +1044,7 @@ ata_sg_is_last(struct scatterlist *sg, struct ata_queued_cmd *qc)
                 return 1;
         if (qc->pad_len)
                 return 0;
-        if (((sg - qc->__sg) + 1) == qc->n_elem)
+        if (qc->n_iter == qc->n_elem)
                 return 1;
         return 0;
 }
@@ -1051,6 +1052,7 @@ ata_sg_is_last(struct scatterlist *sg, struct ata_queued_cmd *qc)
 static inline struct scatterlist *
 ata_qc_first_sg(struct ata_queued_cmd *qc)
 {
+        qc->n_iter = 0;
         if (qc->n_elem)
                 return qc->__sg;
         if (qc->pad_len)
@@ -1063,8 +1065,8 @@ ata_qc_next_sg(struct scatterlist *sg, struct ata_queued_cmd *qc)
 {
         if (sg == &qc->pad_sgent)
                 return NULL;
-        if (++sg - qc->__sg < qc->n_elem)
-                return sg;
+        if (++qc->n_iter < qc->n_elem)
+                return sg_next(sg);
         if (qc->pad_len)
                 return &qc->pad_sgent;
         return NULL;
@@ -1309,9 +1311,11 @@ static inline void ata_qc_reinit(struct ata_queued_cmd *qc)
         qc->dma_dir = DMA_NONE;
         qc->__sg = NULL;
         qc->flags = 0;
-        qc->cursg = qc->cursg_ofs = 0;
+        qc->cursg = NULL;
+        qc->cursg_ofs = 0;
         qc->nbytes = qc->curbytes = 0;
         qc->n_elem = 0;
+        qc->n_iter = 0;
         qc->err_mask = 0;
         qc->pad_len = 0;
         qc->sect_size = ATA_SECT_SIZE;